5G NR Transport Block Size (TBS) Calculator
Calculate exact 3GPP TS 38.214 compliant Transport Block Size (TBS) from allocated resource elements, modulation scheme, code rate, and MIMO layers.
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Inputs
Live
Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
N_info = N_RE × Q_m × R × v; TBS derived per 3GPP TS 38.214 quantisation and LDPC segmentation rulesThis formula is used to calculate antenna parameters for 5g nr transport block size (tbs) calculator.
Overview
Use this 5G NR Transport Block Size (TBS) calculator to determine the payload capacity (in bits and bytes) of a 5G physical channel per slot according to 3GPP TS 38.214 specifications.
Input Guide
Enter Allocated Resource Elements (N_RE), Modulation Order (Q_m), Target Code Rate (R), MIMO Spatial Layers (v) exactly in the units shown by this 5g nr transport block size (tbs). Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Allocated Resource Elements (N_RE).
- Modulation Order (Q_m) — use bits/sym.
- Target Code Rate (R).
- MIMO Spatial Layers (v) — use layers.
Output Guide
The results describe the calculated 5g nr transport block size (tbs) values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The 5G NR Transport Block Size (TBS) uses N_info = N_RE × Q_m × R × v; TBS derived per 3GPP TS 38.214 quantisation and LDPC segmentation rules. Supply Allocated Resource Elements (N_RE), Modulation Order (Q_m) (bits/sym), Target Code Rate (R), MIMO Spatial Layers (v) (layers) in the displayed units, then use the calculated values as the first engineering target for this 5g nr design or analysis.
Design Notes
The initial unquantised bit count (N_info) is calculated from allocated Resource Elements (N_RE), Modulation Order (Q_m), Target Code Rate (R), and Layers (v). 3GPP then applies specific quantisation formulas and byte-alignment to fit LDPC code block segmentation limits.
Build and Tuning Notes
When calculating throughput, multiply the single-slot TBS by the number of active slots per second (e.g., 1,000 slots/s for 15 kHz subcarrier spacing, 2,000 slots/s for 30 kHz SCS).
Frequently Asked Questions
What is the maximum Modulation Order (Q_m) supported in 5G NR?
3GPP Release 15/16 supports up to Q_m = 8 (256QAM). Release 17 added Q_m = 10 (1024QAM) for specialized high-SINR links.
Why does 3GPP quantise the raw N_info bit calculation?
Quantisation ensures the Transport Block Size aligns cleanly with LDPC (Low-Density Parity-Check) base graph segmentations and 8-bit byte boundaries.
How do MIMO layers affect TBS?
TBS scales linearly with the number of MIMO spatial transmission layers (v), effectively doubling capacity when moving from 2-layer to 4-layer MIMO.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.